Ferrite toroid motors are a form of brushless D.C. motor and are fully described in copending U.S. patent application Ser. No. 703,388 filed Feb. 20, 1985, (now U.S. Pat. No. 4,605,874) assigned to the assignee hereof, the disclosure of which is incorporated herein by reference. As is set forth in detail in said copending U.S. patent application, the novel brushless D.C. dynamoelectric machine described therein comprises a disk-like rotor element comprising hard ferrite toroid means providing a plurality of magnetic poles of alternating polarity and mounted for rotation about its axis; a disk-like stator element comprising soft ferrite toroid means and mounted coaxially with and spaced apart from the rotor element, the soft ferrite toroid means being formed with radially-directed coil winding receiving slots; and electrical coil windings mounted to the stator in the slots and each spanning one rotor pole pitch.
Such ferrite motors operate from a D.C. electrical power source by means of electronic control circuits. The functioning of conventional brushless motor/control systems is determined largely by control logic circuits and electronic power switching devices, the timing of which is controlled by the logic circuits. These controls tend to be sophisticated and often are much more expensive to build than the motors which they control, particularly with small motors.
Toroid motors are inherently suited to automated mass production as described in the above-mentioned U.S. copending patent application, and, therefore, are functionally attractive for use in consumer products, such as automobiles or household appliances. In these applications, however, low manufacturing costs are necessary to ensure widespread market acceptance, both in terms of the motor and the control circuit.
There exists a need, therefore, for a very simple control circuit utilizing low cost electronic elements for use in controlling toroid motors, in particular, and electric motors, in general.